JPH07503070A - Fiber optic gyroscope modulation error reduction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Background of the invention of fiber optic gyroscope modulation error reduction TECHNICAL FIELD The present invention relates to an optical fiber device phase modulator, and more specifically, to a state A device for performing such phase modulation of an electromagnetic wave propagating inside as its state changes. It is related to.

A fiber optic gyroscope uses a rotation of the object supporting the gyroscope. It is an attractive means to detect rotation. Such gyroscopes are extremely small Can be fabricated to withstand significant mechanical shock, significant temperature changes, and other extreme environments. It can be made to withstand environmental conditions. Since there are no moving parts, they require little maintenance. It has the potential to be economical in terms of cost. They are a different kind of light It is also sensitive to low rotational speeds, which is a problem with scientific gyroscopes.

The fiber optic gyroscope is centered on the axis, which is the center of rotation to be detected. It has a coiled optical fiber that is wound around a core. The typical length of optical fiber is It is about 100 to 2000 meters and is part of a closed optical path. Electric M in the optical path I-waves, or light waves, are introduced and travel in opposite directions through the coil, ultimately resulting in optical detection. The wave is split into a pair of waves that enter the output device. Detection of core or coiled optical fibers For one such wave, by rotation about the axis, in a certain rotational direction In the opposite direction, the optical path length is effectively lengthened, and in the opposite direction, the optical path length is effectively shortened. another direction The opposite result occurs. Due to the difference in optical path length, such as between waves (one shift of rotation) A phase shift is also introduced between the waves in the orientation, i.e. the well-known Sani This is the Yak effect. The amount of phase difference transition due to rotation, that is, the position of the output signal is different from each other. depends on the total length of the optical path through the coil followed by two electromagnetic waves traveling in opposite directions. Therefore, a large phase difference can be obtained with a long optical fiber, but it is possible to obtain a large phase difference with a long optical fiber. As a result, the volume occupied is relatively small.

The output current from the photodiode of the photodetector device runs the coiled optical fibers in opposite directions to each other. It follows a raised cosine function in response to electromagnetic waves that are incident on the detector after propagating in a direction.

That is, the output current depends on the cosine of the phase difference between the two waves. cosine function Since is an even function, such an output function does not indicate the relative direction of the phase shift. Therefore, the direction of rotation about the coil axis is not shown. Also, near zero phase The rate of change of the cosine function at Always low.

the phase of two electromagnetic waves traveling in opposite directions due to their unsatisfactory properties The difference is that the optical phase modulator, sometimes called a bias modulator, is It is modulated by placing it in the optical path on one side of a loop-shaped optical fiber. the result, One of the waves, traveling in opposite directions, passes through the modulator while traveling through the coil. , other waves traveling in the opposite direction through the coil pass through the transformer 14 on exiting the coil.

Also, tjl! A phase-sensitive detector functioning as part of the feather device detects the photodetector output. Provided to receive a signal representing an electric current. Reduces the amplitude modulation performed by the modulator phase modulators and phase-sensitive detectors to reduce or eliminate the so-called "proper" frequency It can be operated by a sine signal generator in numbers, but other waves of the same fundamental frequency Shape types can also be used. Other steps to reduce frequency to more manageable values frequencies can be used, and often other frequencies.

The resulting signal output of a phase sensitive detector follows a sinusoidal function, i.e. the output signal is The phase difference between the two electromagnetic waves incident on the photodiode is mainly due to rotation about the axis of the coil when no undesired phase difference occurs. depends on the sine of the phase shift. The rate of change of the sine function is maximum when the phase shift is zero. Therefore, it is an odd function that algebraically varies the sine on both sides of the zero phase transition. did Therefore, the phase-sensitive detector signal depends on which direction rotation about the coil axis occurs. maximum change in signal value as a function of rotation speed near zero rotation speed. i.e. the output signal of the detector is The sensitivity of the detector is highest for phase shifts near zero, so that the sensitivity is high. too Of course, this is due to other causes, i.e. if the phase shift due to the error is small enough Only possible. Also, this output signal in those environments is In terms of speed, Jl is always close to a straight line. its relative to the output signal of the phase sensitive detector. These characteristics are a significant improvement over the output current characteristics of a photodetector without prior phase shift X. Ru.

An example of such a device from the prior art is shown in FIG. The optical part of the device device is reversible, i.e., as will be discussed later, the phase difference transition is not reversible. Almost identical optical paths result for each electromagnetic wave traveling in the opposite direction, except for the introduction of the characteristic . A coiled optical fiber is a single piece of optical fiber that is wound around an axis that forms the center of rotation to be detected. Using a one-mode optical fiber, the core module forms a coil 10 around the spool.

Uniquely defines the electromagnetic wave or optical path by using single mode optical fiber and can also uniquely define the phase front of such a guided wave. . This greatly assists in maintaining reversibility.

Also, unavoidable mechanical stress, Faraday effects in magnetic fields, or is the changing phase between waves propagating in opposite directions caused by other sources. The fiber is A very large birefringence is formed inside. Therefore, other optical components in the device In order to propagate electromagnetic waves through , or a lower rate is selected. In this device, the optical components used here are The slow axis was selected taking into account the

The electromagnetic waves that propagate in opposite directions within the coil 10 are the electromagnetic wave source in FIG. source 11. This source is typically a laser diode. Lasada Iodes are typically in the near infrared of the spectrum, with a typical wavelength of 830 nm. Supplies electromagnetic waves in the line part. Rayleigh on the scattering side of the coil 10 and source 1 in order to reduce the phase shift difference between those waves due to Fresnel scattering. 1 must have a short coherent wavelength for the emitted light. coil 1 Due to the nonlinear Kerr effect in zero, the difference in the strength of two electromagnetic waves propagating in opposite directions However, the phase difference between them may be different. This situation is based on source 11 This can also be overcome by having a short coherent wavelength. Then the formal Phase shift cancellation will be performed.

A coil 10 is formed between the laser diode 11 and the optical fiber coil 10. At some point, the end of an optical fiber is separated from the entire optical path into several optical path sections. 1 is shown extending between the optical coupling parts of FIG. Polarization A portion of the maintenance optical fiber is directed to the laser diode 11 at the optimum light emission point. be positioned. The optical fiber runs from that point to the first optical directional coupler 12. Extend.

Optical directional coupler 12 includes an optical transmission medium. This optical transmission medium consists of four boats. I am being courted in between. Two points are on each end of the medium, in Figure 1 the coupler 12 at each end. one of those boats positioned against it The laser diode 11 has an optical fiber extending from the laser diode 11. optical Another boat at the sensing end of the tropic coupler 12 has a Another optical fiber is shown. The optical fiber is a photodetector device 111 4, extending so as to be positioned relative to the photodiode +3 electrically connected to Ru.

The photodiode 13 receives light incident from an optical fiber positioned opposite to the photodiode 13. It receives electromagnetic waves or light waves and supplies photocurrent in response. This photocurrent is In the case of two incident nearly coherent light waves, such a pair provides a photocurrent output that depends on the cosine of the phase difference between nearly coherent light waves of It follows the cosine function when . This photovoltaic device has a very low impedance operates to provide a photocurrent that is a linear function of the incident radiation, typically p-1. -n photodiode.

Optical directional coupler 12 has another optical fiber in the other end boat.

The optical fiber extends to polarizer I5. Other ports on the same side of coupler 12 In the optical fiber, the non-reflective termination [11B is The existing optical directional coupler 12 receives electromagnetic waves or light on any of its boats, and Approximately half of the combiner 1202 at its opposite end from the one with the incoming boat. Appear on each of the two boats. On the other hand, at the same end of the coupler 12 as the incoming light boat, No such wave or light is sent to the boat in the water.

The reason why polarization 111t15 is used is that even in single spatial mode fiber , because two polarization modes are possible in a 1Mi wave passing through the fiber. did Therefore, one of those polarization modes is passed through the optical fiber along the slow axis. , a polarizer 15 is provided for the purpose of blocking other polarization modes. However, polarizer 1 5 completely blocks light in the one polarization state it is intended to block. isn't it.

Also, for this reason, there is a small impossibility between the two electromagnetic waves traveling in opposite directions inside the device. Since an antiphase shift is caused, there is a small irreversible phase shift between those electromagnetic waves. A difference is made. The irreversible phase shift difference is the state of the environment in which the polarizer is placed. It may change depending on. In this regard, the high Birefringence again helps to reduce this resulting phase difference, as mentioned above. Polarizer 15 has boats at either end of it. Electromagnetic wave transmission medium is one of them. located between the boats in the section. Out of the boat at the end of it, the optical side Another optical fiber on the opposite side of the boat from the one connected to the directional coupler 12. part is located. The optical fiber extends to another optical directional coupler 17. lengthen The optical directional coupler has the same wave transmission characteristics as coupler 12.

The boat at the same end of the coupler 17 with the boat coupled to the polarizer 15 However, using a separate optical fiber section, a non-reflective termination device ll! 18. Conclusion Considering the boat at the other end of the combiner 17, one has light in the coil 10. It is connected to an optical component in an optical path extending from one end of the fiber. other bow is connected directly to the remaining end of optical fiber 10. between the coil 10 and the coupler 17 , on the opposite side of the coil lO to the side that is directly coupled to the interface, there is an optical phase A modulator 19 is provided. The optical phase modulator 19 includes both ends thereof in FIG. The transmission medium shown has two ports at each end. coil l The optical fiber from O is attached to the boat of modulator 19. Extending from coupler 17 A length of optical fiber is attached to the other end of modulator 19.

The photometer 19 receives electrical signals and uses those electrical signals to transmit signals to a transmission medium or By changing the refractive index of a plurality of transmission media, the length of the optical path passing through the medium is changed.

This introduces a phase difference into the electromagnetic waves being transmitted. those electrical signals is supplied to the transformer 19 by the bias modulation signal generator 20. That bias change The modulation signal generator generates a sinusoidal voltage output signal at a modulation frequency f. its modulation frequency The number is intended to be equal to C,5in(ω,1). Here, ω9 is equal to the radian frequency of the modulation frequency f. Other suitable periodic waveforms can also be used instead.

This allows the electromagnetic or light waves emitted by the source I+ to The description f1 of the optical part of the device shown in FIG. 1 is now completed. such t4 The magnetic waves are coupled from their source through an optical fiber section to an optical directional coupler 12. .

Some of the wave entering the coupler 12 from source 11 couples into the boat on the opposite side of it. The rest of the wave is lost at the non-reflective termination 9111B, which is 5 to the optical directional coupler 17.

Combiner 17 functions as a beam splitter. In this beam splitter, the polarization It divides the electromagnetic waves received from light 115 and entering the boat approximately in half. on the other hand A portion of comes out of each boat of the two boats at each end of it. join 2117 The electromagnetic waves from one boat at the other end are connected to an optical fiber coil 10 and a modulator 19. through which it returns to the coupler 17. Therefore, a part of this returning wave is transmitted to the polarizer of the coupler 17. to the non-reflective armor r1118 connected to the other boat at the connection end of 15. The rest of the wave passes through the other boat of coupler 17 and is lost to polarizer 15. It reaches a combiner 12 where a part of it is sent to a photodiode 13. polarizer 1 The other part of the wave sent from 5h) to the coil 10 is transmitted to the other boat of the coil 10. Leaves the end of coupler I7 and passes through modulator +9 and optical fiber coil IO to coupler 17 and again, part of it follows the same path as the other part and eventually The light enters the photodiode 13.

As mentioned above, the photodiode 13 receives two electromagnetic waves or light waves incident on it. is proportional to the strength, so the following formula %formula%)] The phase difference between the two electromagnetic waves incident on the diode is given by It provides an output photocurrent, IPD, that follows the cosine. The reason is , whose current is the result of two nearly coherent waves incident on the photodiode +3 The peak value of the light is ■. , how much construction between the two waves FI) or to a smaller value depending on whether destructive interference occurs. This is because it depends on strength. This wave interference causes the coil 10 to form a It changes with the rotation of the coiled optical fiber about its axis. That's because that time This is because the rotation introduces a phase shift φ8 between the waves. Furthermore, this photodiode An additional variable phase shift with an amplitude value of φ1 is introduced into the output current of the mode by the modulator 19. be done. Its additional variable phase shift is intended to vary as COS (ω, 1) be done.

The optical phase modulator 19 is of the type described above, and has a cosine function as described above. Photodetector that follows numbers! 1! To convert the output signal of 14 into a signal that follows a sine function It is used in conjunction with a phase-sensitive detector as part of a demodulator. such a sine According to the function, the output signal corresponds to the rotation about the axis of the coil 10, as described above. Provides information about speed and direction of rotation.

In this way, the output signal of the photodetector f14, which includes the photodiode 13, is a voltage is converted into a and is sent to the phase sensitive detector means 23. Phase acting as part of a phase demodulator The sensing detector means 23 are well known devices. Such a phase sensitive detector device is filtered the amplitude of the first harmonic of the output signal of the photodiode device, or the modulation signal generator The amplitude of the fundamental frequency of 20 is taken out and the electromagnetic wave incident on the photodiode 13 is provides an indication of the relative phase of. This information is a phase-sensitive output signal that follows a sine function. is supplied by the sensor 23. That is, this output signal is sent to the photodiode 13. It follows the sine of the phase difference between the two incident electromagnetic waves.

The bias modulator signal generator 20 modulates the light in the optical path at the frequency f. , the high voltage being generated by the recombined electromagnetic waves at the photodetector r1114. It also leads to harmonic components. The filter 22 detects the frequency components of the output signal of the photodetector 14, In other words, it is a bandpass filter that passes the first harmonic after it has been amplified by the amplifier 21. .

During operation, two electromagnetic waves traveling in opposite directions pass through the coil 10 in the optical path. Due to the rotation, the change in phase difference caused by the modulator 19 is changes relatively gradually. What phase due to rotation, or sagnac light waveization, The difference also simply changes the phase difference between the two electromagnetic waves. Output of filter 22 amplitude conversion coefficient of the modulation frequency component of the output signal of the photodetector 114 appearing at the output terminal a) the amplitude value of the phase modulation of those waves by modulator 19 and generator 20; b) this phase difference further modified by a factor with constants representing the various gains in the device; It is expected to be set by the sine of . Then, the occurrence in this signal component The periodic action of this sinusoidal modulation by the modulator 20 and the modulator 19 causes the demodulator [11 (detection (a) includes a phase-sensitive detector 23, depending only on the amplitude conversion factor of the output signal; It is removed by demodulation in the device and demodulated steamer fi! (Detector) Leaves an output signal.

Therefore, the voltage at the output terminal of amplifier 2I is: V71-aut=k(1+ It typically appears as cos[φ8+φm(ωot10)co). Is the coefficient C a device? It represents the gain from the output terminal of the amplifier 21 to the output terminal of the amplifier 21. The symbol θ is supplied by the generator 20 represents the additional phase delay in the output signal of amplifier 21 with respect to the phase of the signal. This phase Some with a transition are introduced into the photodetector 14, and some are introduced into the modulator 19. , the phase of the signal provided by the generator 20 and the refractive index of the medium in the modulator 19 and its between the length of the modulator 19 and therefore the response of the modulator 19 when having a change. from other sources such as the phase shift of used in the previous formula Other symbols in have the same meanings as they have in the first formula above.

The second equation can be expanded using Bessel series expansion to give the following equation.

V, +-0,, = k C1 + J o (φ-) cosφ a]-2kJ, ( φ,) sinφp CO9((’)*j10)-2kJ? (φ,) CO 3-, cos2 (ω, t+θ) + 2kJ3 (φ,) sinφRCO33 ( ω, L10) + (I)’2k J2. , −+ (φ,,) sinφ* cos(2n+1)(ω, is 10)] This signal at the output terminal of the amplifier 21 is As described above, the filter 22 primarily Pass the first harmonic from the latter equation, ie, the modulation frequency component. As a result, the fill The output signal of the controller 22 can be written as: V, 2-,,,=-2kJI (φ,) sinφ, cos (ω, 10+ Another phase delay term A, which appears in A,) is added as a result of passing through the filter 22. is the additional phase difference in the first harmonic term. This additional phase difference is approximately constant; It is predicted that i! is a known characteristic of the filter 22. I+ will be given.

The signal from filter 22 is then filtered like the signal from bias modulator generator 2o. The signal is then applied to the phase sensitive detector 23. The latter is equal to C+5in(ωl, 1) It is once again intended to be Here, ω. is equal to the modulation frequency f, It is a radian frequency. A phase shift equal to θ+vl is detected by the phase sensitive detector 23. If it is possible to add to the output signal, the output signal of the generator 20 as well as its detection The output of the generator will be something like this:

V, , ,, = to' J, (φ,) sinφ.

The constant ' is the device gain including the phase sensitive detector 23.

However, those predicted results may not be achieved with the apparatus of FIG.

One reason why the expected results cannot be achieved is that the bias signal generator 20 When the light in the optical path is modulated at the frequency f9 by the phase modulator 19, it is recombined. As a result, harmonic components are generated in the photodetector 114 due to the emitted electromagnetic waves. Not only that, but also non-linearity is generated in the generator 20 and modulator 18. This is because the result is that the harmonic components in the changing optical path phase are directly supplied. .

That is, the first possibility is that the signal supplied by the modulation generator 20 to its output terminal is the output signal contains not only the fundamental signal of frequency f, but also its important harmonics. There is. Even if it is possible to provide a signal that does not contain such harmonics, the phase modulator 1 Due to the non-linear component characteristics and hysteresis in This may result in the introduction of such harmonics into the phase that changes. Like that Large rate fluctuations occur in the fiber optic gyroscope output signal due to high harmonics. This may result in bias errors. Therefore, the An interferometric fiber optic gyroscope in which errors such as is desired.

Wl essential for invention In the present invention, the optical fibers are transmitted in opposite directions through the coiled optical fiber, and have a certain phase relationship. Error control for optical fiber rotation sensor based on electromagnetic waves incident on photodetector at It provides equipment. These electromagnetic waves propagating in opposite directions are phase modulated The sensor output signal passes through a bias optical phase modulator operated by a generator. may contribute to second harmonic distortion that causes errors in the process. acceptable sensor In order to obtain or the combination of limiting factors and contributions below the equivalent output error limit. Indirect limitations based on factors can be used. Modulation with a piezoelectric material wrapped around an optical fiber section Control of the bias optical phase modulator contribution of the piezoelectric layer with nonlinear stiffness This is done by attaching the .

Brief explanation of FIIJ surface Figure 1 shows a system of the present invention that combines a signal processing device, an optical transmission line, and an equipment rIIW4 configuration. System outline 1Iry:J is shown.

2A and 2B illustrate a modulator device of the present invention.

Detailed description of the preferred embodiment Typically, the phase shift of the bias modulation subsystem is applied to the optical path into and out of the coil. j! in the time-varying phase applied by I9 and modulation generator 120. The next harmonic after the fundamental is large enough to cause a large error. Create a high amplitude. Therefore, only the second harmonic needs to be considered. Therefore, Eliminating the second harmonic, the output signal, in particular, rather than as c+5in(ω,1) Then, V>o=c2 [cosω, t+δ, cos(2ωat+W',)] No measures can be taken to provide an output signal with a larger output voltage amplitude that varies with First, the modulation signal generator 20 can be considered. Change from sine function representation to cosine function representation It is FiB's choice.

In this representation of the output signal of the generator 20, δ is the rarefaction relative to the amplitude of the fundamental component. The relative amplitude of the unwanted second harmonic signal that distorts the desired output, C2 is the generator is the overall gain constant of . Its gain constant changes the fundamental output signal from it to the desired amplitude. Set to a value of 1-minute to supply width. For generation of second harmonic signal component The generated phase W′, is relative to an arbitrarily selected zero phase value for the fundamental signal. and was selected by Nl1i.

The phase transformer 19 can be composed of a ceramic material body exhibiting a piezoelectric effect, and what is surrounding it? F r. This ceramic body is typically made of lead norcotitanate (PZT). A hollow cylinder (ring) made of material is cut into pieces, and the rings are connected to each other. a cylindrical shape with cut electrical leads leading to interconnection with the generator 20; One is typically placed on the outer curved surface and one on the inner curved surface of the object. electrical Under excitation, the ring can become less (and partially accustomed) to the equivalent electrical circuit element. Works as an electrical circuit element.

The basic signal from the modulation generator R20 causes the ceramic ring to expand and contract radially. Then, the outer curved surface of the ring is stretched and wrapped around the ring. Stretch the optical fiber, and relax such stretching to run it's length Extend and contract. This action vibrationally changes the optical path length in the optical fiber. This modulates the phase of any electromagnetic waves passing through it.

Alternatively, the phase modulator 18 is typically a titanium or proton diffused exchanger. It has a substrate made of lithium lead niobate (LiNbOs) with a waveguide. It can be constructed from an integrated optical chip. The modulation generator 20 has an electro-optic effect. It is connected to a pair of electrodes on both sides of the waveguide that performs phase modulation internally. They are electrically interconnected by electrical leads. of electromagnetic waves traveling along a waveguide The phase is applied by the electrodes in response to the output signal of the generator 20 applied to the electrodes. As the electric field is varied, the effective refractive index in the waveguide section between it is electro-optically to modulate those electromagnetic waves. Electrical with integrated optical chip The operation of the physical components is also indicated at their electrodes on the chip substrate. They are equal valence electrical circuit elements, again primarily capacitive, at least partially simulated by light Such devices selected for use in fiber gyroscopes The output voltage of modulation generator 20 to either V2. If you add , the optical path part of the device The phase φ(1) of the electromagnetic wave passing through is changed over time. Gyros selected to be reflected with a time-varying phase change in the optical path of the cop device. the second harmonic in the output signal of the modulation generator 20 which is passed through the phase modulator device The wave component as well as the required relatively large voltage component of the fundamental component of this generator output signal. Applying a pressure amplitude to such a device causes another second harmonic component to vary in its time. The mechanical response that typically feeds into a phase change is then generated. Ru. Therefore, the electromagnetic waves traveling along the optical path of the phase modulator device used are The time-varying phase change caused by the bias modulator that is subjected to φ(t) "C2φ, CO5ω, t+c2φ2δ, cos(2ω, t+tF,)+C2 φ, δ, cos(2ω, t+ψt). In this resulting phase response The amplitude response of the phase modulator 19 is the first harmonic modulation in the optical path portion of the modulator. of the output signal of the modulation generator 2o applied to the modulator upon conversion to the The effect of the first harmonic change component is φ, which includes electromechanical and mechano-optical effects. It is. The result of converting the effect applied to the phase change in the optical path section of the modulator 19 , the direct response of the modulator 19 to the second high IR wave component of the output signal of the modulation generator 20. A time-varying phase second harmonic component arises due to the line amplitude response. This response is It is named φ2. This response φ again includes electromechanical and mechano-optic effects. nothing.

Another time-varying phase second harmonic component modulates the output signal of modulation generator 20. 1619 into a phase change in the optical path portion of the modulation generator 20. Also due to the non-linear amplitude response of its modulator 19 which seals to the first harmonic component of the output signal. arise. An application that converts the generator first harmonic component into a time-varying first harmonic component. The magnitude of the response to the answer is named δ. This temporally changing second harmonic The reason why the wave component is generated is mechanical non-direction to the first harmonic component that changes over time. This is because linearity is the highest. Electrical stimulation of phase transformer I9 at the second harmonic frequency Since there may be a phase shift between the mechanical response and the The phase type in the optical path phase change component that changes as follows is the phase type of the output signal of the modulation generator 20. Note that this is different from the phase ψ' in the second harmonic (consisting of two harmonics). corresponding temporal The mechanical nonlinearity that produces the second harmonic optical path phase change component that changes to The non-linear behavior of the M4W material in the phase modulator 19 and the This typically occurs due to the relationship between hysteresis and structural components, e.g. mechanical connections. Ru.

After passing through the coil 10 and the phase modulator 19, they are recombined in the coupler 17. The net irreversible phase difference φ, (t) between electromagnetic waves propagating in opposite directions is φ(1) − φ(t−γ). Here, γ is the electromagnetic wave leaving the modulator 19 and proceeding through the coil 10. , is the length of time it takes to reach the symmetric point on the opposite side of the coil. .

This definition for φ, (t) is to substitute t based on LΔL′+τ/2. By handling the equation for this electric current more conveniently, we can make it symmetrical. .

The length of time is such that the Ti magnetic wave is symmetrical from the phase modulator 19 to the other side of the coil 10. is the propagation time through the coil 10 to the point where . Using the definition of φyuN), and and the above substitution gives the following result.

φ, (1)=φD)−φ(t−τ) =φ(t'+τ/2)-φ(t'-τ/2) for tAt'+τ/2=C 2φ + [cos (ω, t' ten. τ/2) - cos (ω, t' - ω. τ/2 )] +C7φ2δs[cOs(2ω9t' +ω9τ+ψG)-cos(2's lIt ′-ωヮτ+heavy #)ko+C7φ, δm Ccos (2ω, t’ + ωaτ +1vj-cos(2ω, tl+ω1τ1kō,)]”-2’C2φ+sin (ω9τ/2) sinω. t'-2C9φ, δ# Sln (ωaτ) si n (2ω,, t’+ψe)-20, φ1δ, sin (at ω9) sin ( 2ω, t′ + muff) Here, the last equation is obtained using the trigonometric identity. . The amplitude of the fundamental harmonic peak changes 31 amplitude φY, or φ, , A-2C2φ, sin Assuming that ω9τ/2 is defined, this last equation can be rewritten as I can do it.

φ・(t')=φ, sinω,, t'+2δ7φ, cos (ω.τ/2) sin(2ω, t’+IF,) The electromagnetic wave with this phase reaches the photodetector 13 and is To use this last phase difference, the above equation for ipv can be changed to this approximation. To arrive at this, we must use trigonometric identities and transform ourselves. That is, the above equation can be expanded using Bessel series expansion. The Bessel series is combined with the trigonometric identity As a result, the following first harmonic component appears in the output of the photodetector 13.

Since the first harmonic signal from the modulation generator 20 follows the cosine of ω1L, φ=0 , that is, any phase difference at zero rotation speed can be estimated as an error. of the modulation generator 20, assuming that we ignore any rotation of the coil IO so that At the fundamental frequency, the in-phase component of the last equation is transferred to the phase-sensitive detector 23 ( sinω, the term multiplied by t').

V, i-0゜, = k' φ, cos (ω9τ/2) [J, (φ,)-J3 (φ5)] The constant ' appears again in the first equation of ■, 3-0°, given to -. n:i of the phase sensitive detector 23 and internal device components. This covers the gain constant.

Therefore, as the equation for the extracted in-phase signal component shows, the phase sensitive detector 23 There is an offset value in the output signal of Output value indicating the rotational speed of that coil even though there is no input rotational speed either exists. However, the subsequent signal processing circuit to which the gyroscope is connected is , given by the first equation above based on the absence of second harmonic distortion. be configured to receive the signal V21-eut in the expected manner. Dew. That is, V23-, u, = is equal to 'J, (φ,) based on sinφR rotation speed. It is determined that it is a thing. Therefore, those last two are obtained and the valid rotation Sent as speed. This value is ni′ノ, (φ, ) s r n cicada = /2′ This result is useful The rotational speed error φR was kept relatively small due to the use of a gyroscope. This can be easily done based on the assumption that Then offset rotation The speed error is directly A phase shifter based on a ceramic body wrapped around an optical fiber and using a fused coupler. A relatively slow-performance optical fiber with an output error of several degrees per hour is used. An open-loop interferometer optical fiber configured to provide a fiber gyroscope. Consider fiber gyroscopes. Such a configuration has a bias modulation frequency or the frequency of the fundamental component of the output signal of the modulation generator 20 is also controlled to within kilohertz. limit

In those environments, a base bias is applied to maximize the expected output signal. If the typical value of the amplitude of the modulation component amplitude φ8 is selected as 1.84, then yields a value of the order of I. Therefore, the equation can be very well approximated by the following equation.

Given the typical allowed error for such devices of several degrees per hour, φ8 is typically specified as φ2〉io−′, or. Obviously, this failure If equality must be satisfied, then each term on the right side of this inequality represents an inequality individually. must be fulfilled. In other words, it is made of ceramic with optical fiber wrapped around it. In a phase modulator composed of a loop ring, the second harmonic frequency is generated in the optical path passing through it. The response in a time-varying phase change that occurs at It only takes 10 minutes! Therefore, φ, /φ, = O, I typically found. The coefficient A, can never be greater than 1, and the coefficient A, The assumption is that the unmeasurable change will always take on an arbitrary value less than 1. prevent. Therefore, for the error analysis giving the result that δ, :a10-5 , the value 5inlF, must be treated as approximately 1.

δ, w-weird! of the second harmonic component of the output signal provided by the lid generator 20. Since the amplitude of the first harmonic component is χ・j, the second harmonic component is equal to the amplitude of the fundamental component. 1oOdb lower than the amplitude (i.e. for the modulation generator 20) so that the specification for system output error is reduced by a factor of 20 dB from the specification for system output error. , the mechanical response of the phase modulator is the second harmonic generated by the modulation generator 20. It fully supports suppressing the FW of components.

On the other hand, since the result is δ, ≦l0-6, due to the unpredictability of sin 'F- We have to consider it again to be about 1. Therefore, δ is the time The nonlinear mechanism of the phase modulator 19 for the first harmonic optical path phase change component that changes Is it the amplitude of the first harmonic optical path phase change component that changes over time due to the physical response? , the mechanically induced second harmonic phase change component amplitude is the fundamental harmonic light It must be 120 dB lower than the amplitude of the road phase change component.

The requirement for the output signal of the modulation generator 20, δ, ≦10−5 or -100 dB is at least at a frequency twice the fundamental frequency ω9 of the output signal of the generator 20. It is fed after being passed through a filter with a sufficient number of poles to attenuate it by 100dB. This can be achieved by Such a filter uses a phase modulator 18 over the range of voltage amplitudes required to be supplied by the generator for operation. It must be constructed of elements that do not exhibit non-linear operation. Such a configuration The ratio of the amplitude of the second harmonic component to the main component is the optical fiber gyroscope shown in Fig. 1. Output signal smaller than the phase error allowed at the rotational speed for the coping device will occur.

The mechanical The requirement was met using a structure with a ceramic ring around which the optical fiber was wrapped several times. It can be much more difficult to accomplish. Ceramic embodiment is separated into basic The vibration mode at component frequency 1 is the back and forth radial vibration motion of the outer surface of the ring. The number 8 pattern is designed to prevent the outer periphery from changing due to the movement. In that it follows objects, it is well suited to the vibration mode for the periodic motion of the ring, but An even bigger problem arises. motion (any constraint on a ring is may cause small deformations and generate other harmonic components during motion. These harmonic components are converted into the stretching motion of the optical fiber that is wound around it. It will be done. Due to the consequent effects of such changes in the length dimension of the fiber, the optical path phase A second harmonic component is generated during the change, and a second harmonic component is generated in the electromagnetic wave passing through it. is induced.

One such constraint is the interconnect wires being fixed to the ring. their mutual contact 1ull applies a mechanical load to the ring, more specifically an unbalanced mechanical load. Add. A typically much more severe source of unbalance constraints fixes the ring in the desired location. A number of keyaki mounts can potentially be used to convey that ring. It is a load. Finally, wrapping the optical fiber around the ring is subject to load constraints, especially sources of hysteresis and radially vibrating rings and periodic variations in temperature; temporally due to the stretching process of the fiber due to the movement that occurs as a result of aging. Due to varying mechanical imbalances and/or non-uniform weighting constraints. This could be the cause. Such hysteresis is due to inhomogeneities in the ceramic material in the annulus. and/or other harmful effects. those The key nonlinearity contributes to forming the value of δ, and more specifically, the second height Harmonics and especially hysteresis contribute to the formation of 1-.

Figures 28 and 2B show that hysteresis and other mechanical imbalances are The optical phase is configured to significantly reduce those types of nonlinearities, including 3A and 3B respectively show a top view and a cross-sectional side view of the modulator. PZT ceramic ring 30 It is shown positioned in a recessed portion of housing 31.

The concave part is the size of the flat eave on the top surface of this housing.

This hole is formed by the outer vertical side of the circular cross section formed by the housing 31. surrounded. The central part of this hole is approximately parallel to the upper surface of the housing 3I, and the upper surface thereof There is a central core 32 in the form of a right cylinder that strikes two surfaces "higher than the upper surface."

An open cell on the F side, i.e. a soft foam layer 33 is provided on the bottom of this hole. It will be done. A central hole in the layer allows the core 32 to extend upwardly through it. Ru. A ring 30 of ceramic material is placed around the core 32.

The ring 30 is made of another open cell, disc-shaped, soft foam with the same thickness as the ring 30. The material layer 34 maintains it approximately centered relative to this core. in the foam material layer 34 The hole also allows core 34 to extend therethrough.

The upper open cell, i.e., soft foam layer 35 covers the top surface of layer 34 and annulus 30. The core 32 is disposed over a large portion of the core 32 and extends upwardly through it. It will be done. A fixing plate 36 with a fixing hole in the center is attached to most of the ring 30 and layer 35. , placed on all of the core 32 except for the core part that is made into a cylinder by the fixing hole. I am made to do so. The male screw 37 is screwed into the fixing hole 36 of the fixing plate 36, and the core It is inserted into the screw hole provided in the center of the top surface.

Turn the screw 37 until the fixing plate 36 is firmly pressed against the upper surface of the core 32. this Operation allows repeatable depth of the hole in the housing 31 and repeatable height of the core 32. given the height of the rings, determined by the height of the rings and the thickness of their layers. A repeatable downward force is applied to the annulus 30 between the open cells and the soft foam layer 35.3. Added to the combination with 3. In this way, the force holding the ring 30 is is fairly well known and fairly repeatable.

135 and 33 act as somewhat nonlinear springs, and ring 30 is considerably It is lightly held, the stiffness in those layers is very small, and the rings are If it is at the center between them, it will resist the force of the ring applied to those layers. but , for example, by mechanical impact, i.e. the orientation of any of those layers When moved a large distance and the layers become relatively stiff, the rings added to their shoulders The resistance of those layers to force increases very quickly. Ring 30 heads towards core 32 is moved in the radial direction, the center l1134 acts in a similar manner. do. This relatively light load on the annulus 30 is due to the annulus being forced by the generator 20. Although it suppresses the generation of second harmonic components during periodic motion, it still causes a relatively large amount of vibration. Keeps the annulus 30 well restrained from dynamic amplitudes.

A pair of flexible rods are provided to electrically connect the inner curved surface and the outer curved surface of the ring 30, respectively. The sex line 38.39 is used. The interconnection wires 38, 39 can be bent very well. Therefore, almost no mechanical load is applied to the ring 30. Interconnection line 38.3 A possible alternative to the ring, which helps avoid the loads imposed by It is a solid disk of solid ceramic material. This is because such a disk is in periodic motion. by generating a stationary nodal location under and fixing those lines to that stationary nodal location. This is because it does not interfere with the movement of the disk.

An optical fiber extending between the coupling n27 and the coil 10 wound around the ring 30 FIG. A and FIG. 2B. The optical fiber 4o on the outer curved surface of the ring 30 is wound. Flexible to the upper part! 139 is connected. The light that is wrapped around) To significantly reduce the hysteresis and slippage during the elongation process during modulation, The outer sheath of the optical fiber portion 40 is thin and hard, and requires good glue force and adhesion to the core. be.

Also for this purpose, a section of optical fiber 40 is placed approximately around the outer curved surface of the ring 30. Rolled down to a tension of 40 grams. The winding process is made using epoxy that can be cured by ultraviolet light. This is done by moistening the surface. The epoxy is applied through a section of wound optical fiber. and then cured to firmly bond the portion to the outer curved surface of the ring 30.

To avoid stretching only a portion of the loop in the optical fiber 40 around the annulus 30, the optical Fiber portion 40 is wrapped symmetrically around the outer surface of ring 30 an integral number of turns. .

As a result of such a structure of the phase modulator 19, the mechanical response occurs at a second height. The harmonic component is mechanically induced with an amplitude less than 80 dB than the fundamental frequency component amplitude. It is relatively easy to have a temporally varying second harmonic optical path phase change. If you achieve this and are careful, the amplitude will be 120 dB or more smaller than the amplitude of the fundamental component. A phase modulator will be obtained which will have . In this way, FIG. 2A1 The phase shifter of FIG. No more second harmonic phase than allowed for the offset phase error component The requirement of supplying variable components can be met.

The expression found above for the offset phase error due to the presence of the second harmonic component also presents two further possibilities for reducing or eliminating such offset errors. It is. The first one is found in the coefficient [1-J3 (φ,)/J, (φ,)] issued. Maximize the amplitude of the fundamental component of the phase change φ1 to maximize the predicted output signal. By choosing a value of 3.05 that is sufficiently higher than the value of 1.84 used for The coefficient can be brought to zero, or very close to zero. This results in φ 2 also becomes zero. The device that selects and maintains the amplitude value of the bias modulation fundamental component is “Optical Fiber Book Gyroscope Bias Modulation Vibration” by Dane et al. Width determination (Fiber 0ptic Gyroscope Bias Module ation Amplitude Determination) J name 11m0 for pending U.S. patents filed earlier and assigned to the same assignee as the present application. 7/636.305. I include it here for reference. the The device cannot maintain the bias variation jltM width perfectly at 3.05, and The offset due to the higher quadrature signal increases, but due to this factor, it is not zero but , this device can be used to supply relatively small values. It then If the Iba gyroscope output signal offset phase error specification remains unchanged However, the limits that δ and δ7 must satisfy can be raised.

Eliminate the offset phase error shown in the equation found for this purpose. Other possibilities remain to significantly reduce the coefficient e08ω1τ/2 Provided by. As is well known, a modulation generator 20 operates a phase modulator 19. There is a so-called "natural frequency" for ω9 when Its modulation frequency In terms of wave numbers, the modulation of electromagnetic waves propagating in opposite directions through the coil 10 has a phase of 1. 80 degrees different. It provides tremendous benefits to the operation of the bias modulator. ω. Ma Or ω. The natural frequency for -2 is ω, -2τ=π. at that frequency The phase modulator of the type described in Figures 2A and 2B has a typical frequency of Cannot operate normally. This is the relatively short length used to form coil 10. for long lengths of optical fiber (although it is also applicable to longer lengths). ), therefore one choice is especially a coiled fiber optic gyroscope. If no loop is involved, an integrated optical chip phase shifter may be used. Is Rukoto.

If the typical value of φ, 1,84 is again used, then [+−J3( φ, )/J, (φ, )] will again be approximately 1. On the other hand, integrated optical chips Using a dip eliminates the assistance from the mechanical response ratio, i.e., φ, /φ .

is approximately 1. This is because the integrated optical chip has a capacitance between the electrodes. Electricity that does not introduce large frequency-dependent effects until they become large at very high frequencies This is because it exhibits a wide bandwidth when using optical effects. As a result, due to δ, The support of this factor brought about in raising the limit to be met is eliminated. Furthermore , δ, are approximately zero, making it possible to use integrated optical chips of arbitrary size. There would be no mechanically induced second harmonic component difficulties in child The results show that the photoelastic effect in the object in such a chip is comparable to the electro-optic effect. This is because it is relatively small. Such an integrated optical chip suffers from the transverse axis effect (qu Other non-linearities that result in only a drature effect) are shown. So Paying attention again to the fact that the value of 1 must be considered, the error phase can be expressed as 1φm l,,,=cos(ω.τ/2)δ.

It can be written as

However, τ is the temperature for the optical fiber of the coil lO, which expands and contracts due to temperature changes. Since it is a function of degree, setting COS (ω.τ/2) to zero or ω ,/2 to π/2 presents great difficulties. Typically, This temperature dependence is (1/τ)dτ/dTmi10-5/℃ This is the order. Here, T represents the temperature in degrees Celsius. Due to this temperature dependence, eos (ω.

τ/2) yielding a corresponding temperature dependence. It is ω which is about π/2.

For τ/2, Show that dcos(ω.π/2)/dT=(-π/2)10-5/℃. I can do it. Therefore, cos (ω.τ /2) will change by the following values:

1ΔCog((Ll, lτ/2)l=60Xπ/2XIO-5=IO-3 but Therefore, predict how close Co5 ((+), τ/2) will remain to zero 10-3. Therefore, the phase of the second harmonic component with respect to the first harmonic component from the modulation generator is The requirement for relative amplitude is such that the phase modulator 19 is operated at its natural frequency. 60 dB is less severe in certain situations. This is an optical fiber wrapped around or a coil using such a ceramic body and windings. Using integrated optical circuits rather than long lengths of optical fiber in This is achieved by On the other hand, integrated optical chips and long lengths of optical fibers The cost of using at least one of the fiber optics I (Gyros) Such a gyroscope to be able to sell the coop at the required cost significantly lower, or to just a fraction of once per hour. can be reduced to In the context of an integrated optical chip, the modulation generator 20 The requirement for the amplitude δ of the second harmonic component relative to the first harmonic component supplied by is 1φ*1. , is less than 10-5 than in the previous situation. It's not right.

In many situations, modulation generator 20 will be required to operate phase modulator 19. It is more convenient to provide a square wave rather than a string wave. For example, as shown in the apparatus of Figure 1. In some u1 harmonics, which are different from those shown, the waveform is very convenient. There is. Such a square wave, if it is a true square wave, contains no even harmonics. , therefore, the harmonics and second harmonics that are likely to be important when operating the phase modulator 19 Only harmonics do not exist.

Furthermore, it is very difficult to provide a square wave to drive a capacitive load. Yes, especially at higher frequencies. 50% duty cycle Duty cycles other than 1 are not a major difficulty. Because such non- This is because a symmetrical square wave simply gives rise to a quadrature signal which is supplied by the phase detector. be. On the other hand, the rise and fall times of a square or square wave are not equal. Then, the second harmonic component is generated and causes an offset phase error. Become. the fundamental component of the resulting second harmonic component δ from the generator 20; The limits for the allowed optical fibers are as shown in the above formula for ・Remains related to the gyroscope phase error limit, where δ, = (rise can be shown to be related to (rise time−rise time)/τ. coil The length of 10 is 1. If OK is selected, τ is approximately 5 μs. δ, is required If we have to satisfy δ, ≦10-5 again, then the wave rise time and The difference in rise time does not exceed 0.05 ns.

Although the present invention has been described above with reference to preferred embodiments, it is possible to deviate from the gist and scope of the invention. Without doing, aspect and! Those skilled in the art are able to make drastic changes to the details. You'll understand.

International search report orT/IK cnznn7,7 front page continuation (72) Inventor: August, Richard Gei United States of America 85254 Arishina, Scotsbuil North, 56 T.H. Brace 1261 2 (72) Inventor Dimant, Kevin Bee United States of America 85020A Rishina State/Fex North Dreamy Drow Drive Number 129.7557 (72) Inventor Aing, Dick Elka, Grendill West, Alisina, 85302, United States of America Minido (72) Inventor Blake, James N. United States 850 32 Alisina FEX East Fleece Drive 4416 (72) Inventor: Fess, John Earle United States of America 85023 Alishi NA・FEX NORTH 6TH AVENUE 15811

Claims (1)

[Claims] 1. They are propagated in opposite directions through a coiled optical fiber (10) to a photodetector (13) in a phase relationship with an effective maximum offset error related to the determined maximum rotational speed off-yet error. A rotation sensor (Fig. 1) that detects rotation about the axis of a coiled optical fiber (10) (coil axis perpendicular to the page) based on incident electromagnetic waves has an input terminal. , reaches the optical fiber (10) wound into a coil on the optical path up to the photodetector (13), and or biased optical phase modulator means (19) arranged in selected optical path sections followed by electromagnetic waves emanating from said coiled optical fiber (10); biasing the electromagnetic waves traveling along said optical path through optical phase modulator means (19) so as to impart a varying phase difference to the electromagnetic waves traveling in opposite directions, in response to corresponding electrical signals at the input terminals; Phase modulation is possible, and if the corresponding electrical signal is approximately periodic at a first frequency, then the varying phase changes at a frequency twice that of the first frequency. a biased optical phase modulator having an amplitude that is a first portion of its amplitude at the biased optical phase modulator means, and an output terminal electrically connected to an input terminal of the biased optical phase modulator means; a second part of the amplitude of the fundamental component with a fundamental frequency and a fundamental component of the selected amplitude, and at a frequency twice the fundamental frequency; phase modulation generator means (20) capable of supplying to said output terminal a substantially periodic electrical output signal having a high frequency component with a range of about 100 Hz, and electrically connected to said photodetector (13); The output representing the arbitrary phase difference that occurs between a pair of electromagnetic waves incident on it. and a detection input terminal for receiving signals from the detection input terminal, and an output terminal for causing a signal representing an amplitude of a component of a signal generated based on the fundamental frequency to appear at the output terminal. a signal component selection means (14, 21, 22) capable of causing a signal representing the amplitude of a component of a signal occurring at the detection input terminal to appear at the output terminal based on the fundamental frequency thereof; Said biasing optical phase modulator means (19) is adapted to be coiled in response to said phase modulation generator means (20) providing an output signal of said phase modulation generator means (20) to said output terminal thereof. providing a varying phase difference at said fundamental frequency between electromagnetic waves of fundamental phase difference amplitude propagating in opposite directions in said optical fiber (10), said first part and said second part maximum o A rotation sensor comprising signal component selection means (14, 21, 22) whose value is lower than the ratio of the offset error to the basic phase difference amplitude. 2. Rotation sensor according to claim 1, wherein the required value for the second part is achieved by filter means in the phase modulation generator means (20), the output signal of said phase modulation generator means is supplied through a filter means, and said filter means is supplied with a frequency at a frequency twice said fundamental frequency; The amplitude of several components is fed through a selected attenuation factor, said fundamental frequency. A rotation sensor that can reduce the amplitude of a number of signal components below. 3. The rotation sensor according to claim 1, wherein the rotation sensor is required for the first part. The value of the biased optical phase modulator means is achieved by said biased optical phase modulator means having an input terminal and a peripheral portion whose length is variable in response to an electrical signal applied to said input terminal. a piezoelectric material structure means (30) having a surface of revolution with a shape, a length of optical fiber (40) insertable into the optical path and forming a coil wound around said surface of revolution; resistance to compression increases sufficiently The pressure between the pair of compression-resisting interface layers (33, 35) and said pair of interface layers (33, 35) inside thereof increases significantly with increasing pressure. A rotation sensor comprising fixing means (32, 36, 37) to which an electrical material structure means (30) is mounted. 4. Rotation sensor according to claim 1, wherein the output signal of said phase modulation generator means (20) approximates a rectangular waveform, said second portion occurring between said rise time and said fall time. the electromagnetic wave is biased from the optical phase modulator means (19) through the coiled optical fiber (10) to the opposite side of the coiled optical fiber (10). of the rotation sensor divided by the length of time required to propagate to the point of symmetry in the optical path between them. 5. 2. A rotary jancer as claimed in claim 1, wherein said signal component selection means (14, 21, 22) is configured to electrically connect said signal component selection means (14, 21, 22) to its output terminal for receiving said output signal from said phase modulation generator means (20). the signal component selection means (14, 21, 22) is supplied with the demodulation input terminal and selects a selected demodulation frequency; A rotary jancer capable of using a signal having a sufficient number of demodulated signal components to cause a signal to appear at its output terminal, based on the demodulation frequency, representing the amplitude of the signal occurring at its input terminal. 6. are propagated in opposite directions through a coiled optical fiber (10) and incident on a photodetector (13) in a phase relationship with an effective maximum offset error related to the determined maximum rotational speed offset error. This is a rotation sensor (Fig. 1) that can detect the rotation of a coiled optical fiber (10) about its axis (coil axis perpendicular to the page) based on electromagnetic waves generated by the sensor. and placed in a selected optical path portion of the optical path portion followed by electromagnetic waves that reach or exit the coiled optical fiber (10) on the optical path up to the photodetector (13). difference biased optical phase modulator means (19), wherein the biased optical phase modulator means (19) The electromagnetic waves propagating along said optical path are passed through bias optical phase modulator means (19) so as to give a varying phase difference to the electromagnetic waves propagating in opposite directions in said optical fiber (10). phase shift in response to a corresponding electrical signal at and the corresponding electrical signal is substantially periodic at a first frequency. Bias light whose phase changes at a frequency twice the first frequency has an amplitude that is a first portion of the amplitude that the changing phase has at the first frequency. an optical phase modulator and an electrical connection to the input terminal of the bias optical phase modulator means; has an output terminal connected to the fundamental component of the selected fundamental frequency and the selected amplitude. a substantially periodic electrical output signal having a frequency of twice the fundamental frequency and having a high frequency component with an amplitude that is a second fraction of the amplitude of the fundamental component. detection means (20) electrically connected to said photodetector (13) and receiving therefrom an output representative of any phase difference occurring between a pair of electromagnetic waves incident thereon; a signal component selection means (14) having an input terminal and an output terminal and capable of causing a signal representing the amplitude of a component of a signal generated based on the fundamental frequency to appear at the output terminal; , 21, 22), wherein a signal representing the amplitude of a component of a signal occurring at the detection input terminal based on the fundamental frequency appears at its output terminal, and the biasing optical phase modulator means (19) said optical fibers (10) wound in a coil in response to said phase modulation generator means (20) for supplying an output signal of said phase modulation generator means (20) to said output terminal thereof; At the fundamental frequency between the electromagnetic waves with the fundamental phase difference amplitude transmitted to biasing said optical phase modulator means (19); and said phase modulation generator means (20) comprises a small portion of said first part and said second part. providing weighting coefficients forming a product over at least one of the first parts; , the remaining one of the second portion, and the product of the effective maximum offset. smaller than the ratio between the cut error and the fundamental phase difference amplitude, and before being used to form the product. one of the first portion and the second portion is greater than the output ratio; minute selection means (14, 21, 22). 7. 7. The rotation sensor according to claim 6, wherein both the first portion and the second portion have a second portion that corresponds to the corresponding first portion by crossing the weighting coefficient. the first product and the second product both have values less than the power ratio, and both the first portion and the second portion have a rotational speed greater than the power ratio. Nsa. 8. 7. The rotation sensor according to claim 6, wherein the weighting coefficient is based on a response ratio. and said bias optical phase modulator means (19) is configured to provide said phase modulation generator means output signal to said output terminal of said phase modulation generator means (20). responsive to modulation generator means for providing a varying phase at a grid frequency in an electromagnetic wave of fundamental phase difference amplitude traveling in said coiled optical fiber (10); (20) in response to said phase modulation generator means supplying a periodic signal with a frequency twice the fundamental frequency to said output terminal of said coiled optical fiber (10). further providing a varying phase at a frequency twice said fundamental frequency in a propagating high frequency phase amplitude electromagnetic wave, said frequency ratio being equal to said high frequency phase amplitude; Rotation sensor equal to the ratio of the frequency phase amplitude to the fundamental frequency amplitude. 9. 7. Rotation sensor according to claim 6, wherein said signal component selection means (14, 21, 22) are adapted to receive said output signal from said phase modulation generator means (20) to said phase modulation generator means (20). a demodulation input terminal electrically connected to the signal generator; The minute selection means (14, 21, 22) are provided with a selection signal supplied to said demodulation input terminal thereof. Using a signal having sufficient demodulated signal components at the selected demodulating frequency, A rotation sensor capable of causing a signal representative of the amplitude of a component occurring at an input/output terminal to appear at its output terminal in response to the demodulation frequency. 10. 8. The rotation sensor according to claim 7, wherein the weighting factor is based on (ω■τ/2), where ω■ is the fundamental frequency and the selected temperature range is is kept within a selected range centered at π/τ over the from the optical phase modulator means (19) through the coiled optical fiber (10) to the opposite side of the coiled optical fiber (10); The rotation sensor is the time required to propagate to a symmetrical point in the optical path. 11. 8. The rotation sensor according to claim 7, wherein the weighting coefficient is based on [J1(φ)−J,(φ)], where φ is the basic phase difference amplitude and the selected The rotary yancer is maintained within a selected range centered at 3.05 over a selected temperature range. 12. 9. A rotation sensor according to claim 8, wherein the value for the response ratio is determined by the bias optical phase modulator means, the bias optical phase modulator means having an input terminal and a bias optical phase modulator means provided to the input terminal. changes length in response to an electrical signal a piezoelectric material structure means (30) having a surface of rotation with a peripheral edge capable of a length of optical fiber that can be inserted into the path and forms a coil that is wound around the rotating surface; (40) can be compressed, but the resistance to compression increases with sufficient increase in compression. A piezoelectric material structure means (30) is mounted between a pair of compression-resisting interface layers (33, 35) and inside said pair of interface layers (33, 35) so as to increase in width. A rotation sensor comprising fixing means (32, 36, 37) such as: 13. 11. Rotation sensor according to claim 10, wherein the output signal of the phase modulation generator means (20) approximates a rectangular waveform, and the second portion is characterized by a difference between the rise time and the pre-fall time. The electromagnetic wave is passed from the bias optical phase modulator means (19) through the coiled optical fiber (10) to the opposite side of the coiled optical fiber (10). side, to a point of symmetry in the optical path between them. The rotational flux is approximately equal to the length of time it takes to propagate. 14. to be located in the optical path, through it, and to propagate along that optical path. A biased optical phase modulator (FIGS. 2A and 2B) capable of phase modulating electromagnetic waves generated by the oscilloscope, which includes an input terminal and a peripheral portion whose length can be changed in response to an electrical signal applied to the input terminal. a piezoelectric structure means (30) having a rotating surface and a length of optical fiber insertable into the optical path and forming a coil wound around said rotating surface; a fiber (40), a pair of interface layers (33, 35) capable of compression but resistant to compression such that the resistance to compression increases significantly with a sufficient increase in compression; and fixing means (32, 36, 37) between which the piezoelectric material structure means (30) are mounted. Preparation equipment. 15. 15. The bias optical phase modulator according to claim 14, wherein the pair of optical phase modulators The optical phase modulators (33, 35) are each formed of a soft foam material. 16. Biased optical phase modulator according to claim 14, characterized in that the piezoelectric material structure means (30) are configured as a layered structure and are compressible, such that the resistance to compression increases significantly with a sufficient increase in compression. , a non-linear stiffness that resists compression further comprising a centering ring (84) having a centering ring (34), the centering ring (34) having a rigid A bias light positioned inside said piezoelectric ring structure means (30) around a. logical phase modulator. 17. 15. A bias optical phase modulator as claimed in claim 14, wherein said length of optical fiber (40) has a thin, adhesive jacket around its periphery. 18. 15. A bias optical phase modulator according to claim 14, wherein said length of optical fiber (40) is spliced to itself and said piezoelectric ring structure means (30). vessel. 19. 15. A bias optical phase modulator according to claim 14, wherein the phase modulation generator means comprises a reciprocal wire which is a flexible wire (38, 39) in a portion proximate to the input terminal of said bias optical phase modulator means. a bias optical phase modulator having an output terminal electrically connected to said bias optical phase modulator means in connection; 20. 16. The bias optical phase modulator of claim 15, wherein the foam is an open cell foam. 21. 17. A bias optical phase modulator according to claim 16, wherein said centering rings (34) are each formed of soft foam. 22. 19. Biased optical phase modulator according to claim 18, characterized in that said length of optical fiber (40) has an uncured adhesive deposited around said length of said piezoelectric material structure means (30). ), and the bonding agent is A biased optical phase modulator that is rolled and then cured. 23. 19. A biased optical phase modulator according to claim 18, wherein said length of biased fiber (40) is wound around said piezoelectric material structure means (30). A biased optical phase modulator with an approximately integer number of turns. 24. 22. The bias optical phase modulator of claim 21, wherein the foam is an open cell foam.